This invention relates to placement and in-situ consolidation of polymer coated multifilament fiber tows in tow placement processes for manufacturing composite parts, and more particularly, it relates to controlling the placement process for manufacturing composite parts of irregular geometry at high throughputs.
U.S. Pat. No. 5,160,568 discloses filament winding of fiber-tow whereby the tow is preheated, tensioned and deposited on a cylindrical mandrel to form composite parts of regular geometry. A published European application EP-0 463 611 A2 discloses the use of a hot shoe and a chilled compaction roller which provides improved degree of consolidation in filament winding on cylindrical mandrel.
EP-491 355-A1 European Publication discloses placement of polymer coated fiber-tows on mandrels having irregular sections and a computer controlled process which employs the use of a hot air-gun which heats the contact area prior to compaction and a computer-model which calculates air flow rate and air temperature needed to maintain a pre-set temperature of the contact area. Although this disclosure discloses a computer controlled process for producing of fiber-reinforced composite parts having irregular geometry, it suffers from the sluggish response of the air-gun heat source and, consequently, it can not maintain the temperature of the contact area at the desired value when the fiber-tow suddenly accelerates or decelerates with the changing geometry, particularly, when the process is run at high speeds, i.e., above 20 ft/min. This results in non-uniform or poor consolidation of the composite part or limits operation of the process to extremely low throughputs.
For optimum feasible low-cost operation, it is desirable that the in-situ consolidation process has a fast heat transfer response to accomodate rapid changes in tow velocity so that the process can be operated at highest possible throughputs.